Double-acting hydraulic hoist



April 18, 1950 v. l. GANDRUP 2,504,406

DOUBLE-ACTING HYDRAULIC HOIST Filed April 22, 1947 Patented Apr. 18, 1950 UNITED STATES PATENT OFFICE 2,504,406 DOUBLE-ACTING HYDRAULIC HOIST Vernon I. Gandrup, Watsonville, Calif. Application April 22, 1947, Serial No. 743,105

2 Claims.

An object of my invention is to provide a double acting hydraulic hoist which dilers from the device shown in my copending application, Ser. No. 738,705, led April 1, 1947. In my copending case, I provide a stationary cylinder and slidably mount a. movable cylinder therein. I further provide a stationary hollow piston rod carried by the stationary cylinder and mount a stationary piston on the rod. The movable cylinder has a closed inner end with a sleeve for slidably receiving the rod and the piston is slidably received in the movable cylinder.

In the copending case, the return for the fluid from the stationary cylinder after the movable cylinder reaches its limit of travel is through a port in the hollow piston rod, uncovered by the sleeve of the movable cylinder. My present invention makes use of a separate passage, external of the stationary cylinder and having its inlet end uncovered when the movable cylinder is fully extended.

I also provide a novel control valve for the external passage and for other inlet and outlet pipes connecting the valve with the two cylinders, whereby a movement of the valve in one direction will cause the iluid to extend the movable cylinder and a movement of the valve in the opposite direction will cause the uid to positively retract the movable cylinder. In addition to this the valve may be moved to an intermediate position for stopping the movable cylinder in its travel at any point desired while being extended or retracted. It is also possible to leave the valve in either of its extreme positions and when the movable cylinder reaches the end of its travel as caused by the particular position of the valve, ports will be uncovered which will permit the uid to continue to ilow to and from the cylinders, thus obviating the necessity of returning the valve to a neutra position when the movable cylinder reaches the end of its stroke.

' The invention is simple in construction and is durable and eicient for the purpose intended.

Other objects and advantages will appear in the following specification, and the novel features of the device will be particularly pointed out in the appended claims.

' My invention is illustrated in the accompanying drawing forming a part of this application, in which:

Figure 1 is a vertical section through the device, the control valve being shown in elevation;

Figure 2 is a longitudinal section through the control valve;

Figure 3 is a horizontal section theline III III of Figure 1;

Figure 4 is an end elevation of the control valve as seen adjacent line IV-IV of Figure 2; and

Figure 5 is a perspective view of the insert for the control valve.

While I have shown only the preferred form of my invention, it should be understood that various changes or modifications may be made within the scope of the appended claims without deipiarting from the spirit and scope of the inven- In carrying out my invention, I provide a stationary cylinder A that has an end plate I secured thereto by bolts 2 or other suitable fastening means. A movable cylinder B is slidably received in the stationary cylinder and a packing gland AI is carried by the cylinder A and makes a liquid tight connection with the outer surface 3 of the movable cylinder B. The outer end of the cylinder B is closed by an end plate 4.

A stationary hollow piston rod C is mounted in the stationary cylinder and is axially aligned therewith. The piston rod has one end secured to the end plate and the movable cylinder B has a closed inner end 5 with a sleeve 6 for slidably receiving the piston rod. A stationary piston is mounted on the free end of the piston rod and is slidably received in the movable cylinder. A liquid receiving compartment 1 is formed in the movable cylinder and is bounded by the closed. end 5 and the piston D. The end plate 4 has an opening 8 therein for permitting air to enter or leave that portion of the movable cylinder E bounded by the piston D and the end plate 4.

One of the novel features of my invention in the present case and also in my copending case is the means for delivering uid under pressure to the compartment I for positively retracting the movable cylinder B. This means includes the hollow piston rod as a conveyor housed within the stationary and movable cylinders for delivering fluid to and for withdrawing it from the compartment 1. The piston rod has an opening 9 communicating with the compartment 1.

By delivering uid to and from the compartment 1 along the aligned axes of both stationary and movable cylinders, it is possible to make the cylinders of any diameter desired. The larger the diameter of the cylinders, the greater the bearing area between the outer surface 3 of the movable cylinder B and the inner contacted area I of the stationary cylinder A. By making the diameters of the cylinders larger, it is also possible to increase the lifting eiect of the taken along -outlet end of the pipe I3.

movable cylinder B and also the retractive force of the same cylinder. Very little lateral play between the cylinders need be overcome, the cylinders themselves providing their own support against this movement.

In order to cause the movable cylinder B to be extended, the end plate I of cylinder A has a, fluid inlet pipe II communicating with the interior of the stationary cylinder. The fluid trapped lin they compartment 'I' during the extension of the movable cylinder will pass through the opening S in the piston rod and enter the interior of the rod. A return fluid pipe I2 for theV rod C has one end secured to the plate I and communicates with the interior of' the rod. When the cylinder B reaches its limit of eX- tension, a return fluid pipe I3 has its entrance end uncovered by the inner end 5 of the movable cylinder and the fluid will flow into this pipe.

I provide a novel control valve E for simultaneously opening the pipes II and I2 and the Before describing *this valve. it is best to state that the cylinder B is positively retracted by forcing fluid through the piston. rod C and into the compartment 'I by means of the opening 9. A fluid inlet pipe Illl communicates with the interior of the rod C. The fluid trapped in the stationary cylinder A during the return of the cylinder B, will flow into an outlet opening I5 disposed near the base of the cylinder and then into a fluid return pipe I6. The same valve E that simultaneously opensv the pipes II, I2 and I3 when the cylinder B'is extended, will open the pipes Ill and I6 and close the pipes II, I2 and I3 when it is desired to' retract the cylinder. When the cylinder B isI fully retracted, an opening Il in the cylinder' walland near the closed end 5 will register with an annular groove Ila, communicates with the pipe I5 with the result that fluid can continue to enter thecompartment 'I and will leave by the fluid return pipe I6.

It isnow best to describe the structure of ther control valve E and then set forth the operationv Referring to Figure 2,v it. control valve has a cylindrical housing I8. A removable insert; indicated generally at E in perspective in Figure 5,. is placed in the housing and is secured in place by cap screws t9 or other suitable fastening means. The insert E has a central and longitudinally` extending cylindrical portion Z in which a valvebody 2l is slidably mounted. The valve body hasthreetransversely extending bores 2IoL',` 2Ib and 2Ic. A lever 22, pivoted at 23 is used for shifting the .valve body 2l along the cylindrical portion 2U.

In Figure 5 I show longitudinally extending and diametrically opposed partitions 24-thatare: integral with the cylinder 20. Figure 4 shows the outer edges of these partitions contacting the inner surface of the valve housing I8 -to form a liquidtight seal. A lower half disc partition 25 divides the lower portion of the housing I8 into an inlet fluid manifold F and an outlet fluid'. manifold G. A fluid inlet pipe 26 leads from a pump, not shown, return-'fluid` pipe Z'I-leads from the return fluid. manifold G to the pump or fluid supply reservoir.. The cylindrical portion 20 has a plurality of openings FI, FZ-:andFS communicating with4 the inlet-manifoldF and a second group of openings GIf,-vG2-and G3 communicating with thereturn of the entire device. will be noted that the manifold: G. The bores 2 la and 2 Ib inthe valveil bod?,r 2-I arei spacedy to'register simultaneously' and an opening I'Ib thatl to the inlet manifold F and-a 4 with the openings FI and GI, F2 and G2, or F3 and G3.

In Figure 5 I show four upper half disc partitions 28, 29, 30 and 3| spaced from each other with the peripheries of these discs making liquid tight seals with the inner surface of the housing I8. The end plate 32 of the valve insert E' cooperates with the half partition 28, the partitions 24 and the housing I8 form a fluid outlet compartment H. An opening I-Ir in the cylindrical portion 2i! places the compartment H in communication with the inlet manifold F when the valve body bore 2 I a registers with the opening H and opening FI'.

A second fluid outlet compartment J is boundedy by the half disc partitions 28 and 29, and an opening J in the cylindrical portion 20 places this compartment in communication with the manifold F when the valve body 2I is shifted for bringing the bore 2I,a into registry with the open-ings .if and F3. The half disc partition 28 lies in the same plane as the lower half disc partition 25;

A fluid inlet compartment K is bounded by the half disc partitions 29 and 30, and this compartment has an opening K in the cylindrical portion 2li that places it in communication with the outlet manifold G when the bore 2-Ib of the valve body 2l communicates with the openings K and GI. A second uid inlet compartment L is bounded by the hal-f disc partitions 30 and 3l, and the compartment has an opening L in the cylindrical portion 20 that places the compartment in communication with the manifold G when the valve body 2l is shifted to bring the bore 2lb into registration with the openings L and G3.

Still another liuid inlet compartment M isA bounded by the half disc 3l and the closed end portion 33 of the housing I8, and the compartment is provided with an opening M in the cylindrical portion 20 that places this compartment in communication with the manifold G when the bore 2Ic of the valve body 2I communicates with the opening M and an opening GII, the latter communicating with the manifold G. Figure 2 shows the pipes II, Id, I2, I6, and i3, reading from right to left, communicating 'with the compartments I-I, J, K, L and M, respectively. The pipes permit the control valve E to be disposed remote from the cylinder A and B if desired and still control the operation of the cylinder B.

The valve E has a bypass 34 whose inlet 34a and outlet 34h register with the bores 2Ia and 2lb when the valve body 2| is shifted into an intermediate position. The bores 2'Ia and 2lb when registering with the ends ofthe bypass in this r'nann'er, also register with the opening" F2 and G2 so that the inlet manifold I1" is` placed direct communication with the outlet manifold G and both are cut off from the cylinders A and' B. The cylinder B will' therefore4 remain inthe position into which it has been moved.

From the foregoing description, of the various parts of the device, the oper-ation thereofl may be readily understood.

The lever 22 for the valve is shoWnin-a position in Figuresy 1 and' 2' for placing the inlet manifold F in communication with the outlet compart` ment I-I and the inlet compartment K incom-- munication with the outlet manifold G. Fluid under pressure will flo through the pipes' 26- and II to enter the cylinder AV and move the cylinder B into the extended position shown-in-Fig.-

ure 1. During the movement of the cylinder B into this extended position, the fluid in the compartment 7 will return through the piston rod C, and the pipes I2 and 21 to the pump or reservoir, not shown.

When the cylinder B reaches its limit of travel. the return pipe I3 will communicate with the interior of the cylinder and fluid will flow from the cylinder A, through the pipe I3, inlet compartment M, opening M', bore 2Ic, opening G4,

and outlet manifold G to the return pipe 21. It is possible to stop the movement of the cylinder B at any point desired between its limits of travel by moving the valve body 2| to its intermediate position where the bores 2Ia and 2lb will communicate with the bypass 34 that connects the inlet manifold F directly with the outlet manifold G. The bore 2Ic will be out of registration with the openings M and G4.

The cylinder B can be positively retracted and the fluid will enter the compartment 'I by means of the piston rod C when the valve body 2| is shifted to cause the bore 2Ia to interconnect the manifold F with the compartment J and the bore 2lb to interconnect the manifold G with the compartment L. Fluid will now flow from the pipe 2B to the pipe I4 and the piston rod C to enter the chamber 1 and retract the cylinder B. The trapped fluid in the cylinder A will flow out through the opening I5, pipe I6, and return through pipe 21.

When the cylinder B reaches its iinal return position, the opening I1 will register with the groove Ila and the uid will enter the opening I'Ib which communicates with the pipe I6. The valve body 2| can be shifted into its intermediate position during the return of the cylinder B by connecting the bores 2 la and 2 Ib with the bypass 34 and the cylinder B 4will be stopped in its travel. The partition 3| may be dispensed with if desired and the compartments L and M combined into one. The hoist may be used as a hydraulic ram.

I claim:

1. A double acting hydraulic hoist comprising a stationary cylinder, a movable cylinder slidably mounted in the stationary cylinder, a hollow piston rod carried by the stationary cylinder, said movable cylinder having a closed end with a sleeve for slidably receiving the piston rod, a piston secured to the piston rod and being slidably received in the movable cylinder, a fluid inlet pipe communicating with the stationary cylinder for delivering fluid under pressure thereinto, a return fluid pipe communicating with the interior of the piston rod, said rod having an opening communicating with the space in the movable cylinder bounded by the piston and the closed end for conveying trapped iuid from this space to the hollow piston rod and return pipe, and a second return pipe communicating with the stationary cylinder at a point where the entrance to this pipe will be uncovered when the movable cylinder is fully extended, whereby fluid can continue to enter the stationary cylinder through the inlet pipe and will leave the cylinder through the second return pipe, a second iiuid inlet pipe communicating with the interior of the hollow piston rod, a third iiuid return pipe for the stationary cylinder, and a control valve for closing the first fluid inlet pipe and the first and second return duid pipes and for opening the second uid inlet pipe and the third return fluid pipe.

2. A double acting hydraulic hoist comprising a stationary cylinder, a movable cylinder slidably received in the stationary cylinder, a hollow piston rod carried by the stationary cylinder, the movable cylinder having a closed end with a sleeve for slidably receiving the rod, a stationary piston carried by the rod and being slidably received in the movable cylinder, a fluid inlet pipe for the stationary cylinder, a return fluid outlet pipe communicating with the stationary cylinder so as to be opened when the movable cylinder is fully extended, the hollow piston rod having an opening communicating with the interior of the movable cylinder bounded by the closed end and piston, a second return pipe communicating with the rod interior for receiving the trapped iiuid in the movable cylinder that enters the rod, a

second inlet pipe communicating with the rod interior, a third return pipe communicating with the stationary cylinder, a valve for closing the first inlet and first and second outlet pipes and for opening the second inlet and third outlet .5, pipes for causing iiuid to enter the space between the closed end and piston for returning the movable cylinder, the movable cylinder having an outlet opening communicating with the third return pipe when the cylinder is fully retracted. VERNON I. GANDRUP.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,294,266 Hogg Feb. 11, 1919 1,548,559 Simpson Aug. 4, 1925 2,184,793 Clench Dec. 26, 1939 2,276,418 Rockwell Mar. 17, 1942 2,392,203 Tucker Jan. 1, 1946 

